#if !defined(YCM) && 1
#define _FORTIFY_SOURCE 0
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC target("avx")
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#include <stdio.h>
#endif

#include <bits/stdc++.h>
#include <unistd.h>
#pragma GCC diagnostic ignored "-Wunused-result"
#pragma GCC diagnostic ignored "-Wunused-function"
using namespace std;
#define ll int64_t
#define ull unsigned long long int
#define clr(a) memset(a,0,sizeof(a))
#define clr_(a) memset(a,-1,sizeof(a))
#define pb(a) push_back(a)
#define pii pair<int,int>

#define eps 1e-9
#define inf INT_MAX
#define pi acos(-1.0)
#define ff first
#define ss second
#define INF (ll)1e18
#define m_p make_pair
#define vsort(v) sort(v.begin(),v.end())
#define all(v) v.begin(),v.end()
int fx[]={0,0,-1,1,-1,1,1,-1};
int fy[]={1,-1,0,0,1,1,-1,-1};
ll lcm(ll a,ll b){return (a/__gcd(a,b))*b;}
ll bigmod(ll a,ll p,ll mod){ll ans=1;while(p){if(p&1)ans=ans*a%mod;a=a*a%mod;p>>=1;}return ans;}
ll power(ll x,ll n){if(n==0)return 1;else if(n%2==0){ll y=power(x,n/2);return y*y;}else return x*power(x,n-1);}

#ifdef shaft
     #define debug(...) __f(#__VA_ARGS__, __VA_ARGS__)
    template < typename Arg1 >
    void __f(const char* name, Arg1&& arg1){
        cerr << name << " is " << arg1 << std::endl;
    }
    template < typename Arg1, typename... Args>
    void __f(const char* names, Arg1&& arg1, Args&&... args){
        const char* comma = strchr(names+1, ',');
        cerr.write(names, comma - names) << " is " << arg1 <<endl;
        __f(comma+1, args...);
    }
#else
    #define debug(...)
#endif
inline int read_char() {
    static char buf[1 << 16], *ptr = buf, *end_ptr = buf;
    if (ptr == end_ptr) {
        int len = fread(buf, 1, sizeof(buf), stdin);
        if (len <= 0) return EOF;
        ptr = buf;
        end_ptr = buf + len;
    }
    return *ptr++;
}

inline int read_int() {
#undef getchar_unlocked
#define getchar_unlocked read_char
    int sg = +1, ch;
    do {
        ch = getchar_unlocked();
        if (ch == '-') sg = -1;
    } while (ch < '0' || ch > '9');
    int x = ch - '0';
    while (true) {
        ch = getchar_unlocked();
        if (ch < '0' || ch > '9') break;
        x = x * 10 + ch - '0';
    }
    return sg * x;
}

void _R(int &x) { x=read_int(); }
void R() {}
template<class T, class... U> void R(T &head, U &... tail) { _R(head); R(tail...); }

template<class T> void _W(const T &x) { cout << x; }
void _W(const int &x) { printf("%d", x); }
void _W(const int64_t &x) { printf("%" PRId64, x); }
void _W(const double &x) { printf("%.16f", x); }
void _W(const char &x) { putchar(x); }
void _W(const char *x) { printf("%s", x); }
template<class T> void _W(const vector<T> &x) { for (auto i = x.begin(); i != x.end(); _W(*i++)) if (i != x.cbegin()) putchar(' '); }
void W() {}
template<class T, class... U> void W(const T &head, const U &... tail) { _W(head); putchar(sizeof...(tail) ? ' ' : '\n'); W(tail...); }

const int N=(int)1e6+5;
ll arr[N];
int main()
{
    //ios_base::sync_with_stdio(0);cin.tie(0);
    #ifdef shaft
        //freopen("in.txt","r",stdin);
        ///freopen("out.txt","w",stdout);
    #endif ///shaft
    ll idx = 1;
    for(int i = 1; i < N; i++)arr[i] = (ll)2*idx-1LL, idx += (ll)i;
    //for(int i = 1; i<=10;i++)debug(arr[i]);
    int k ;
    scanf("%d",&k);
    debug(arr[k]);
    ll sum = (ll)(arr[k]+(k-1))*(ll)k;
    W(sum);
   // printf("%lld\n",sum);
    return 0;
}